Solid-state image sensor and electronic device

ABSTRACT

To control an excess bias to an appropriate value in a light detection device.A solid-state image sensor includes a photodiode, a resistor, and a control circuit. In this solid-state image sensor, the photodiode photoelectrically converts incident light and outputs a photocurrent. Furthermore, in the solid-state image sensor, the resistor is connected to a cathode of the photodiode. Furthermore, in the solid-state image sensor, the control circuit supplies a lower potential to an anode of the photodiode as a potential of the cathode of when the photocurrent flows through the resistor is higher.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of application Ser. No.16/649,808, filed Mar. 23, 2020, which is a 371 National Stage Entry ofInternational Application No.: PCT/JP2018/031438, filed on Aug. 24,2018, which claims the benefit of Japanese Priority Patent ApplicationJP 2017-198122 filed on Oct. 12, 2017, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present technology relates to a solid-state image sensor and anelectronic device. Specifically, the present technology relates to asolid-state image sensor that detects light using a photodiode and anelectronic device.

BACKGROUND ART

Conventionally, a distance measuring method called a time of flight(ToF) method is known in electronic devices having a distance measuringfunction. This ToF method is a method of measuring a distance byirradiating an object with irradiation light from an electronic device,and obtaining a round-trip time until the irradiation light is reflectedand returned to the electronic device. For example, a ToF-type camerathat detects reflected light using a single-photon avalanche diode(SPAD) has been proposed (see, for example, Non-Patent Document 1). TheSPAD is a photodiode in which sensitivity is improved by amplifying aphotocurrent.

Here, the SPAD is used in Geiger mode of applying a reverse bias to acertain voltage or higher. In the Geiger mode, control to keep pull upto apply a constant potential with a power supply on an anode side and aresistance or a constant current on a cathode side is performed. Then,when light is detected, an anode-cathode voltage decreases to abreakdown voltage due to impact ionization, and the SPAD transitionsfrom a high impedance state to a low impedance state. A solid-stateimage sensor can generate ToF data by detecting a change in cathodepotential at that time. When the anode-cathode voltage decreases to thebreakdown voltage, the SPAD becomes high impedance again, and when theSPAD becomes high impedance, the SPAD transitions to the Geiger modeagain by pull up. In such a solid-state image sensor, a pixelcharacteristic is determined by an excess bias. Here, the excess bias isa value obtained by subtracting the breakdown voltage from theanode-cathode voltage in the Geiger mode.

CITATION LIST Non-Patent Document

Non-Patent Document 1: Larry Li, “Time-of-Flight Camera—AnIntroduction”, Texas Instruments, Technical White Paper SLOA190B January2014 Revised May 2014

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the above-described conventional technology, a highly sensitiveavalanche photodiode is used, and thus even weak reflected light can bedetected. However, the excess bias may fluctuate due to a variation inthe breakdown voltage and a temperature. As a result, the excess biasmay become too small and the sensitivity of the photodiode may decrease,and conversely, the excess bias may become too large and dark currentnoise may increase. To suppress the fluctuation in the excess bias dueto the variation in the breakdown voltage and the like, an operator mayperform adjustment for each product but this increases labor. For thisreason, in the above-described conventional technology, it is difficultto suppress the fluctuation in the excess bias due to the variation inthe breakdown voltage and the like.

The present technology has been made in view of such a situation, and anobject of the present technology is to control an excess bias to anappropriate value in a light detection device.

Solutions to Problems

The present technology has been made to solve the above-describedproblem, and the first aspect of the present technology is a solid-stateimage sensor including a photodiode configured to photoelectricallyconvert incident light and output a photocurrent, a resistor connectedto a cathode of the photodiode, and a control circuit configured tosupply a lower potential to an anode of the photodiode as a potential ofthe cathode of when the photocurrent flows through the resistor ishigher. The above configuration exerts an effect of supplying a lowerpotential to the anode of the photodiode as the potential of the cathodeof when the photocurrent flows through the resistor is higher, therebycontrolling the excess bias to an appropriate value.

Furthermore, in the first aspect, a detection circuit configured todetect the potential of the cathode of when the photocurrent flowsthrough the resistor and supply the detected potential to the controlcircuit can be further included. The above configuration exerts aneffect of detecting the potential of the cathode of when thephotocurrent flows.

Furthermore, in the first aspect, the resistor and the photodiode may bedisposed in each of a plurality of pixel circuits, the respectivecathodes of the plurality of pixel circuits may be commonly connected tothe detection circuit, and the detection circuit may detect a minimumvalue of the respective potentials of the cathodes of when thephotocurrent flows through the resistor. The above configuration exertsan effect of supplying a potential according to the minimum value of therespective potentials of the cathodes to the anode of the photodiode.

Furthermore, in the first aspect, a variable capacitor connected to thecathode can be further included. The above configuration exerts aneffect of reducing an error of the cathode potential by the variablecapacitor.

Furthermore, in the first aspect, a transistor configured toshort-circuit both ends of the resistor according to a refresh pulsesignal can be further included, and the control circuit can furthersupply the refresh pulse signal to the transistor immediately beforeincidence of the incident light. The above configuration exerts aneffect of short-circuiting the both ends of the resistor by the refreshpulse signal immediately before the incidence of the incident light.

Furthermore, in the first aspect, the photodiode may be an avalanchephotodiode, and the resistance value of the resistor may be a value atwhich the potential of the cathode is fixed. The above configurationexerts an effect of supplying a potential according to the fixedpotential of the cathode to the anode of the photodiode.

Furthermore, in the first aspect, a comparator configured to compare thepotential of the cathode with a predetermined potential and output acomparison result may be further included, and the control circuit maysupply, to the anode, a lower potential than a potential of a case wherethe potential of the cathode is less than the predetermined potential,in a case where the potential of the cathode is higher than thepredetermined potential, on the basis of the comparison result. Theabove configuration exerts an effect of supplying a potential accordingto the comparison result between the potential of the cathode and thepredetermined potential to the anode of the photodiode.

Furthermore, in the first aspect, the control circuit may count a numberof times of when the potential of the cathode becomes lower than apredetermined threshold value in a predetermined period, and may supply,to the anode, a lower potential than a potential of a case where thenumber of times is larger than a predetermined number of times, in acase where the number of times is less than the predetermined number oftimes. The above configuration exerts an effect of supplying a potentialaccording to the number of times of when the potential of the cathodebecomes lower than the predetermined threshold value to the anode of thephotodiode.

Furthermore, in the first aspect, an inverter configured to invert asignal of the potential of the cathode and output the signal as a pulsesignal may be further included, and the control circuit may supply alower potential to the anode of the photodiode as a pulse width of thepulse signal is shorter. The above configuration exerts an effect ofsupplying a potential according to the pulse width of the pulse signalto the anode of the photodiode.

Furthermore, in the first aspect, one end of the resistor can beconnected to the cathode and the other end of the resistor is connectedto a terminal of a predetermined potential, and the control circuit canmeasure a voltage between the potential of the cathode and thepredetermined potential, and can supply a lower potential to the anodeof the photodiode as the voltage is higher. The above configurationexerts an effect of supplying a potential according to the voltagebetween the potential of the cathode and the predetermined potential tothe anode of the photodiode.

Furthermore, in the first aspect, the resistor and the photodiode can bedisposed in each of a plurality of pixel circuits, and the controlcircuit can set any one of the plurality of pixel circuits to be enabledand measures the voltage between the potential of the cathode of the setpixel circuit and the predetermined potential. The above configurationexerts an effect of supplying a potential according to the potential ofthe cathode of the pixel circuit set to be enabled to the anode of thephotodiode.

Furthermore, the second aspect of the present technology is asolid-state image sensor including a photodiode configured tophotoelectrically convert incident light and output a photocurrent, aresistor connected to a cathode of the photodiode, and a control circuitconfigured to measure a temperature and supply a lower potential to ananode of the photodiode as the temperature is lower. The aboveconfiguration exerts an effect of supplying a lower potential to theanode of the photodiode as the temperature is lower.

Furthermore, the third aspect of the present technology is an electronicdevice including a light emitting unit configured to supply irradiationlight, a photodiode configured to photoelectrically convert reflectedlight with respect to the irradiation light and output a photocurrent, aresistor connected to a cathode of the photodiode, and a control circuitconfigured to supply a lower potential to an anode of the photodiode asa potential of the cathode of when the photocurrent flows through theresistor is higher. The above configuration exerts an effect ofsupplying a lower potential to the anode of the photodiode as thepotential of the cathode of when the photocurrent obtained byphotoelectrically converting the reflected light flows through theresistor is higher.

Effects of the Invention

According to the present technology, an excellent effect of suppressinga fluctuation from an appropriate value of an anode potential of aphotodiode can be exerted in a light detection device. Note that effectsdescribed here are not necessarily limited, and any of effects describedin the present disclosure may be exhibited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration example of adistance measuring module according to a first embodiment of the presenttechnology.

FIG. 2 is a block diagram illustrating a configuration example of asolid-state image sensor according to the first embodiment of thepresent technology.

FIG. 3 is an example of a plan view of a pixel array unit according tothe first embodiment of the present technology.

FIG. 4 is an example of a circuit diagram of a control circuit, alight-shielding pixel circuit, and a monitor pixel circuit according tothe first embodiment of the present technology.

FIG. 5 is an example of a circuit diagram of a non-monitor pixel circuitaccording to the first embodiment of the present technology. FIG. 6 is agraph illustrating an example of a voltage-current characteristic of aphotodiode according to the first embodiment of the present technology.

FIG. 7 is a block diagram illustrating a configuration example of asignal processing unit according to the first embodiment of the presenttechnology.

FIG. 8 is a timing chart illustrating an example of fluctuations in acathode potential and a bottom potential according to the firstembodiment of the present technology.

FIG. 9 is a timing chart illustrating an example of fluctuations in acathode potential, an anode potential, and a pulse signal of when thebottom potential is high according to the first embodiment of thepresent technology.

FIG. 10 is a timing chart illustrating an example of fluctuations in thecathode potential, the anode potential, and the pulse signal of when thebottom potential is low according to the first embodiment of the presenttechnology.

FIG. 11 is a timing chart illustrating an example of fluctuations in alight emission control signal and the pulse signal according to thefirst embodiment of the present technology.

FIG. 12 is a flowchart illustrating an example of an operation of thedistance measuring module according to the first embodiment of thepresent technology.

FIG. 13 is an example of a plan view of a pixel array unit according toa second embodiment of the present technology.

FIG. 14 is an example of a circuit diagram of a light-shielding pixelcircuit and a monitor pixel circuit according to the second embodimentof the present technology.

FIG. 15 is an example of a circuit diagram of a control circuit and amonitor pixel circuit according to a third embodiment of the presenttechnology.

FIG. 16 is an example of a circuit diagram of a monitor pixel circuitaccording to a fourth embodiment of the present technology.

FIG. 17 is a block diagram illustrating a configuration example of acontrol circuit according to the fourth embodiment of the presenttechnology.

FIG. 18 is a graph illustrating an example of a relationship between acathode potential and an anode potential according to the fourthembodiment of the present technology.

FIG. 19 is an example of a circuit diagram of a monitor pixel circuitaccording to a fifth embodiment of the present technology.

FIG. 20 is a block diagram illustrating a configuration example of acontrol circuit according to the fifth embodiment of the presenttechnology.

FIG. 21 is a graph illustrating an example of a relationship between acount value and an anode potential according to the fifth embodiment ofthe present technology.

FIG. 22 is a block diagram illustrating a configuration example of acontrol circuit according to a sixth embodiment of the presenttechnology.

FIG. 23 is a timing chart illustrating an example of operations of thecontrol circuit and a monitor pixel circuit according to the sixthembodiment of the present technology.

FIG. 24 is a block diagram illustrating a configuration example of acontrol circuit according to a seventh embodiment of the presenttechnology.

FIG. 25 is an example of a circuit diagram of a monitor pixel circuitaccording to an eighth embodiment of the present technology.

FIG. 26 is an example of a circuit diagram of a monitor pixel circuitaccording to a ninth embodiment of the present technology.

FIG. 27 is a timing chart illustrating an example of a bottom potentialaccording to the ninth embodiment of the present technology.

FIG. 28 is an example of a circuit diagram of a monitor pixel circuitaccording to a tenth embodiment of the present technology.

FIG. 29 is a block diagram illustrating a configuration example of acontrol circuit according to the tenth embodiment of the presenttechnology.

FIG. 30 is a timing chart illustrating an example of fluctuations in alight emission control signal, a refresh pulse signal, and a bottompotential according to the tenth embodiment of the present technology.

FIG. 31 is an example of a plan view of a pixel array unit according toan eleventh embodiment of the present technology.

FIG. 32 is a block diagram illustrating a configuration example of acontrol circuit according to the eleventh embodiment of the presenttechnology.

FIG. 33 is a graph illustrating an example of a relationship betweentemperature and an anode potential according to the eleventh embodimentof the present technology.

FIG. 34 is a block diagram illustrating a schematic configurationexample of a vehicle control system.

FIG. 35 is an explanatory diagram illustrating an example ofinstallation positions of imaging units.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, modes for implementing the present technology (hereinafterreferred to as embodiments) will be described. Description will be givenaccording to the following order.

1. First Embodiment (an example of controlling an anode potentialaccording to a cathode potential)

2. Second Embodiment (an example of controlling an anode potentialaccording to a minimum value of cathode potentials of a plurality ofmonitor pixels)

3. Third Embodiment (an example of controlling an anode potentialaccording to a fixed cathode potential output by a monitor pixel)

4. Fourth Embodiment (an example of controlling an anode potentialaccording to a comparison result of a cathode potential and apredetermined potential)

5. Fifth Embodiment (an example of controlling an anode potentialaccording to a count value related to a cathode potential)

6. Sixth Embodiment (an example of controlling an anode potentialaccording to a pulse width related to a cathode potential)

7. Seventh Embodiment (an example of controlling an anode potentialaccording to an excess bias related to a cathode potential)

8. Eighth Embodiment (an example of controlling an anode potentialaccording to a cathode potential of an enabled monitor pixel)

9. Ninth Embodiment (an example of controlling an anode potentialaccording to a cathode potential of a monitor pixel to which a variablecapacitor is added)

10. Tenth Embodiment (an example of controlling an anode potentialaccording to a cathode potential of a monitor pixel to which a pulsesignal is supplied)

11. Eleventh Embodiment (an example of controlling an anode potentialaccording to temperature)

12. Application to Moving Body

1. First Embodiment Configuration Example of Distance Measuring Module

FIG. 1 is a block diagram illustrating a configuration example of adistance measuring module 100 according to the first embodiment of thepresent technology. The distance measuring module 100 measures adistance to an object, and includes a light emitting unit 110, asynchronization control unit 120, and a solid-state image sensor 200.The distance measuring module 100 is mounted on a smartphone, a personalcomputer, an in-vehicle device, or the like, and is used for measuring adistance.

The synchronization control unit 120 operates the light emitting unit110 and the solid-state image sensor 200 in synchronization with eachother. The synchronization control unit 120 supplies a clock signalhaving a predetermined frequency (such as 10 to 20 megahertz) as a lightemission control signal CLKp to the light emitting unit 110 and thesolid-state image sensor 200 via signal lines 128 and 129.

The light emitting unit 110 supplies intermittent light as irradiationlight in synchronization with the light emission control signal CLKpfrom the synchronization control unit 120. For example, near infraredlight or the like is used as the irradiation light.

The solid-state image sensor 200 receives reflected light with respectto the irradiation light, and measures a round-trip time from lightemission timing indicated by the light emission control signal CLKp totiming at which the reflected light is received. The solid-state imagesensor 200 calculates the distance to an object from the round-triptime, and generates and outputs distance data indicating the distance.

Configuration Example of Solid-State Image Sensor

FIG. 2 is a block diagram illustrating a configuration example of thesolid-state image sensor 200 according to the first embodiment of thepresent technology. The solid-state image sensor 200 includes a controlcircuit 210, a pixel array unit 240, and a signal processing unit 230.In the pixel array unit 240, a plurality of pixel circuits is arrayed ina two-dimensional lattice manner.

The control circuit 210 controls each potential of the pixel circuit inthe pixel array unit 240. Details of control content will be describedbelow.

The signal processing unit 230 measures the round-trip time for eachpixel circuit on the basis of a signal from the pixel circuit and thelight emission control signal CLKp from the synchronization control unit120, and calculates the distance. The signal processing unit 230generates distance data indicating the distance for each pixel circuitand outputs the distance data to the outside.

FIG. 3 is an example of a plan view of the pixel array unit 240according to the first embodiment of the present technology. A part ofthe pixel array unit 240 is shielded from light, light-shielding pixelcircuits 250 are arrayed in the shielded part, and a monitor pixelcircuit 260 and non-monitor pixel circuits 280 are arrayed in a partthat is not shielded from light. In FIG. 3 , the shaded part is a partof the pixel array unit 240 where the light-shielding pixel circuits 250are arrayed. Furthermore, the total number of the monitor pixel circuit260 and the non-monitor pixel circuits 280 is N (N is an integer of 2 ormore), and the monitor pixel circuit 260 and the non-monitor pixelcircuits 280 are arrayed in a two-dimensional lattice manner.Furthermore, one of the N circuits is the monitor pixel circuit 260, andthe remaining is the non-monitor pixel circuits 280.

Hereinafter, a set of the pixel circuits arrayed in a horizontaldirection is referred to as a “row”, and a set of the pixel circuitsarrayed in a direction perpendicular to the row is referred to as a“column”.

Configuration Example of Pixel Circuit

FIG. 4 is an example of a circuit diagram of the control circuit 210,the light-shielding pixel circuit 250, and the monitor pixel circuit 260according to the first embodiment of the present technology.

The monitor pixel circuit 260 includes a resistor 261, a photodiode 262,an inverter 263, and a transistor 264.

One end of the resistor 261 is connected to a cathode of the photodiode262, and the other end of the resistor 261 is connected to a terminal ofa potential VE. As the transistor 264, for example, an N-type metaloxide semiconductor (MOS) transistor is used. A gate signal GAT having apredetermined potential is applied to a gate of the transistor 264, asource of the transistor 264 is connected to a back gate and a groundterminal, and a drain of the transistor 264 is connected to the cathodeof the photodiode 262 and an input terminal of the inverter 263. Forexample, a low level is set to the gate signal GAT in a row readingperiod.

When reflected light enters the photodiode 262, the photodiode 262photoelectrically converts the incident light and outputs a photocurrentIm. As the photodiode 262, an SPAD is used, for example. SPADfurthermore, an anode potential VSPAD of the photodiode 262 iscontrolled by the control circuit 210.

The inverter 263 inverts a signal of a cathode potential Vs of thephotodiode 262 and outputs the inverted signal to the signal processingunit 230 as a pulse signal OUT. The inverter 263 outputs a low-levelpulse signal OUT in a case where the cathode potential Vs is higher thana predetermined threshold value, and outputs a high-level pulse signalOUT in a case where the cathode potential Vs is equal to or lower thanthe threshold value.

At the incidence of the reflected light, the photocurrent Im from thephotodiode 262 flows through the resistor 261, and the cathode potentialVs drops according to a current value of the photocurrent Im. When thecathode potential Vs at the time of the drop is equal to or lower thanthe threshold value, the inverter 263 outputs the high-level pulsesignal OUT. Therefore, the signal processing unit 230 can detect risingtiming of the pulse signal OUT as light receiving timing. Furthermore,the cathode potential Vs of the monitor pixel circuit 260 is monitoredby the light-shielding pixel circuit 250.

Furthermore, the light-shielding pixel circuit 250 includes a resistor251, a diode 252, and a capacitor 253. The resistor 251 and thecapacitor 253 are connected in series between the terminal of thepotential VE and the ground terminal. Furthermore, a cathode of thediode 252 is connected to the cathode of the photodiode 262, and ananode of the diode 252 is connected to a connection point of theresistor 251 and the capacitor 253.

With the above configuration, the light-shielding pixel circuit 250detects the potential of the cathode at the incidence of the incidentlight as a bottom potential Vbtm. Note that the light-shielding pixelcircuit 250 is an example of a detection circuit described in theclaims.

Furthermore, the control circuit 210 includes a comparator 211 and acorrection diode 212. An inverting input terminal (−) of the comparator211 is connected to the connection point of the resistor 251 and thecapacitor 253, and a non-inverting input terminal (+) of the comparator211 is connected to an anode of the correction diode 212. Apredetermined power supply is connected to a cathode of the correctiondiode 212. Temperature characteristics of the correction diode 212 arethe same as those of the diode 252. An error of a bottom potential Vtmdue to the temperature characteristics of the diode 252 can be correctedby insertion of the correction diode 212.

The comparator 211 generates a lower potential as VSPAD as the bottompotential Vbtm is higher and supplies VSPAD to the anode of thephotodiode 262 according to the following expression.

VSPAD=Av(VDD−Vbtm)

In the above expression, Av represents a gain of the comparator 211, andVDD represents a power supply potential.

FIG. 5 is an example of a circuit diagram of the non-monitor pixelcircuit 280 according to the first embodiment of the present technology.The non-monitor pixel circuit 280 includes a resistor 281, a photodiode282, an inverter 283, and a transistor 284. Connection configurations ofthese elements are similar to those of the monitor pixel circuit 260.However, in the non-monitor pixel circuit 280, a cathode of thephotodiode 282 is not connected to the light-shielding pixel circuit250, and a potential of the cathode is not monitored.

FIG. 6 is a graph illustrating an example of a voltage-currentcharacteristic of the photodiode 262 according to the first embodimentof the present technology. The horizontal axis in FIG. 6 represents thevoltage applied between the anode and the cathode of the photodiode 262,and the vertical axis in FIG. 6 represents the photocurrent from thephotodiode 262. In a case of operating the photodiode 262 in the Geigermode, a negative value, that is, a reverse bias is applied to theanode-cathode voltage of the photodiode 262. In a case of using theabove-described SPAD as the photodiode 262, if the reverse bias is lowerthan a predetermined breakdown voltage, an avalanche breakdown occurs inthe photodiode 262, and the photocurrent is amplified. When a voltagethat is lower by several volts than the breakdown voltage is appliedbetween the anode and the cathode, the gain in amplification becomessubstantially infinite, and one photon becomes able to be detected.

Configuration Example of Signal Processing Unit

FIG. 7 is a block diagram illustrating a configuration example of thesignal processing unit 230 according to the first embodiment of thepresent technology. The signal processing unit 230 includes atime-to-digital converter (TDC) 231 and a distance data generation unit232 for each column.

The TDC 231 measures the time from the light emission timing indicatedby the light emission control signal CLKp to the rising of the pulsesignal OUT from a corresponding column (that is, the light receivingtiming). The TDC 231 supplies a digital signal indicating the measuredtime to the distance data generation unit 232.

The distance data generation unit 232 calculates a distance D to anobject. The distance data generation unit 232 calculates, as a roundtrip time dt, a mode value of times measured by the TDC 231 within eachperiod of a vertical synchronization signal VSYNC having a frequency(such as 30 Hz) lower than the light emission control signal CLKp. Then,the distance data generation unit 232 calculates the distance D usingthe following expression, and outputs distance data indicating thedistance D.

D=c×dt/2

In the above expression, c is light speed, and the unit is meter persecond (m/s). Furthermore, the unit of the distance D is, for example,meter (m), and the unit of the round-trip time dt is, for example,second (s).

FIG. 8 is a timing chart illustrating an example of fluctuations in thecathode potential Vs and the bottom potential Vbtm according to thefirst embodiment of the present technology.

When the reflected light is incident at certain timing T0, thephotocurrent from the photodiode 262 flows through the resistor 261,causing a voltage drop, and the cathode potential Vs decreases. Thelight-shielding pixel circuit 250 outputs the potential at this time tothe control circuit 210 as the bottom potential Vbtm.

Then, when a certain recharge time elapses from the timing T0, thecathode potential Vs returns to the potential before the decrease. Whenthe reflected light is incident at subsequent timing T2, the cathodepotential Vs decreases again. Thereafter, a similar operation isrepeated.

Furthermore, the bottom potential Vbtm slightly increases between thetiming T0 and the timing T2 according to the capacitance of thecapacitor 253. Here, assuming that an actual minimum value of thecathode potential Vs is a true value, the bottom potential Vbtm has aslight error with respect to the true value, but a value close to thetrue value can be output by sufficiently increasing the capacitance ofthe capacitor 253.

FIG. 9 is a timing chart illustrating an example of fluctuations in thecathode potential, the anode potential, and the pulse signal of when thebottom potential is high according to the first embodiment of thepresent technology. When the reflected light is incident at certaintiming T0, the cathode potential Vs drops to the bottom potential Vbtmhigher than a threshold value VT, and returns to the original potentialVE by recharging. Here, the threshold value VT is a voltage fordetermining whether or not the incident light has been incident. Whenthe cathode potential Vs is lower than the threshold value VT, theinverter 263 outputs the high-level pulse signal OUT.

Then, assuming that a voltage (breakdown voltage) of a differencebetween the bottom potential Vbtm and the anode potential VSPAD is VBD,the excess bias fluctuates depending on the variation in the breakdownvoltage VBD and the temperature. The excess bias becomes larger as thebreakdown voltage VBD is higher. Usually, the excess bias is a value atwhich the bottom potential Vbtm becomes smaller than the threshold valueVT.

However, there are some cases where the excess bias fluctuates due tothe variation in the voltage VBD and the temperature, and the bottompotential Vbtm does not become lower than the threshold value VT. Inthis case, the pulse signal OUT does not become a high level althoughthe light is incident, and the subsequent signal processing unit 230 maybecome unable to detect the incident light. Therefore, if the anodepotential is set to a fixed value, the photon detection efficiency (PDE)may decrease. Here, the photon detection efficiency indicates a ratio ofa counted number of photons to the number of incident photons when lightis incident and photon counting is performed. The sensitivity of thephotodiode 262 becomes higher as the photon detection efficiency ishigher.

Therefore, the control circuit 210 lowers the anode potential VSPAD asthe bottom potential Vbtm is higher. Thereby, the voltage VBD becomeshigh, the photocurrent increases, and the excess bias becomes large.Therefore, when light is incident again at the timing T1, the cathodepotential Vs becomes lower than the threshold value VT at the timing T2.Then, when the cathode potential Vs reaches the bottom potential, thecathode potential Vs rises by recharging and becomes equal to or higherthan the threshold value VT at timing T3. Furthermore, the inverter 263outputs the high-level pulse signal OUT between the timing T2 and thetiming T3. As described above, by controlling the anode potential VSPADto be high, the pulse signal OUT rises at the incidence of light.Therefore, the signal processing unit 230 can detect the light and thephoton detection efficiency (PDE) is sufficiently high.

FIG. 10 is a timing chart illustrating an example of fluctuations in thecathode potential, the anode potential, and the pulse signal of when thebottom potential is low according to the first embodiment of the presenttechnology. When the reflected light is incident at certain timing T0,the cathode potential Vs drops and becomes lower than the thresholdvalue VT at the timing T1. Then, the cathode potential Vs drops to thebottom potential Vbtm lower than 0 volts, and thereafter rises byrecharging and becomes higher than the threshold value VT at the timingT2. Furthermore, the inverter 263 outputs the high-level pulse signalOUT between the timing T1 and the timing T2.

When the voltage VBD is sufficiently high, the bottom potential Vbtmbecomes lower than the threshold value VT, so that the incident lightcan be detected as described above. However, if the voltage VBD becomestoo high due to factors such as temperature, detection of incident lightbecomes susceptible to dark current noise. As a result, if the anodepotential is set to a fixed value, a dark count rate (DCR) indicating anerroneous count rate due to dark current noise may increase.Furthermore, there is a possibility of occurrence of latch-up and a highprobability of failure of the photodiode 262.

Therefore, the control circuit 210 increases the anode potential VSPADas the bottom potential Vbtm is lower. Thereby, the voltage VBD becomeslow, the excess bias becomes small, and the bottom potential Vbtmbecomes high. As a result, adverse effects such as an increase in theerroneous count rate (DCR) are suppressed.

However, the bottom potential Vbtm is controlled to be lower than thethreshold value VT. Therefore, when light is incident again at thetiming T3, the cathode potential Vs becomes lower than the thresholdvalue VT at timing T4. Then, when the cathode potential Vs reaches thebottom potential, the cathode potential Vs rises by recharging andbecomes equal to or higher than the threshold value VT at timing T5.Furthermore, the inverter 263 outputs the high-level pulse signal OUTbetween the timing T4 and the timing T5. Therefore, the photon detectionefficiency is maintained at a sufficiently high value.

FIG. 11 is a timing chart illustrating an example of fluctuations in alight emission control signal and the pulse signal according to thefirst embodiment of the present technology. The light emitting unit 110emits light in synchronization with the light emission control signalCLKp, and the solid-state image sensor 200 receives the reflected lightand generates the pulse signal OUT. The time from rising timing Ts ofthe light emission control signal CLKp to rising timing Te of the pulsesignal is a value according to the distance. The solid-state imagesensor 200 calculates the distance D to an object from statisticalamounts (a mode value and the like) of the time.

Operation Example of Distance Measuring Module

FIG. 12 is a flowchart illustrating an example of an operation of thedistance measuring module 100 according to the first embodiment of thepresent technology. This operation is started when, for example, apredetermined application for measuring the distance is executed.

The light emitting unit 110 starts light emission, and the pixel circuitin the solid-state image sensor 200 starts to receive the reflectedlight (step S901).

Furthermore, the control circuit 210 controls the anode potential VSPADaccording to the bottom potential Vbtm (step S902). Furthermore, thesignal processing unit 230 measures the round-trip time (step S903), andcalculates the distance data from the round-trip time (step S904).

After step S904, the solid-state image sensor 200 terminates theoperation for distance measurement. In a case of performing distancemeasurement a plurality of times, steps S901 to S904 are repeatedlyexecuted in synchronization with the vertical synchronization signalVSYNC.

As described above, in the first embodiment of the present technology,the solid-state image sensor 200 supplies the lower anode potentialVSPAD as the bottom potential Vbtm is higher, thereby increasing thephotocurrent from the photodiode 262 as the bottom potential Vbtm ishigher. Thereby, the fluctuation in the excess bias due to the variationin the breakdown voltage (VBD) and the temperature can be suppressed.

2. Second Embodiment

In the above-described first embodiment, the solid-state image sensor200 has only one monitor pixel circuit 260 disposed in the pixel arrayunit 240, but there is a possibility of a failure of the monitor pixelcircuit 260 due to, for example, deterioration over time, and the pixelbecomes a defective pixel. A pixel array unit 240 of a second embodimentis different from that of the first embodiment in arranging a pluralityof monitor pixel circuits 260.

FIG. 13 is an example of a plan view of the pixel array unit 240according to the second embodiment of the present technology. The pixelarray unit 240 is different from that of the first embodiment inarranging two or more monitor pixel circuits 260.

For example, one row of the pixel array unit 240 includes M (M is aninteger from 2 to N, exclusive of N) monitor pixel circuits 260, andnon-monitor pixel circuits 280 are arrayed in the remaining rows.

FIG. 14 is an example of a circuit diagram of a light-shielding pixelcircuit 250 and the monitor pixel circuits 260 according to the secondembodiment of the present technology. The M monitor pixel circuits 260are commonly connected to the light-shielding pixel circuit 250. Thelight-shielding pixel circuit 250 is provided with a diode 252 for eachmonitor pixel circuit 260.

Respective cathodes of the diodes 252 are connected to the correspondingmonitor pixel circuits 260, and anodes of the diodes 252 are commonlyconnected to a connection point of a resistor 251 and a capacitor 253.

With the above configuration, the light-shielding pixel circuit 250 candetect a minimum value of a cathode potential of each of the pluralityof monitor pixel circuits 260 as a bottom potential Vbtm.

As described above, according to the second embodiment of the presenttechnology, a solid-state image sensor 200 detects the minimum value ofthe cathode potential of each of the plurality of monitor pixel circuits260, thereby controlling an excess bias to an appropriate value even ifa failure occurs in any of the monitor pixel circuits 260.

3. Third Embodiment

In the above-described first embodiment, the solid-state image sensor200 has detected the bottom potential Vbtm using the light-shieldingpixel circuit 250 provided with the capacitor 253 and the diode 252.However, there is a possibility of an increase in circuit scale due toaddition of the circuit such as the capacitor 253. From the viewpoint ofreducing a mounting area of the solid-state image sensor 200, a smallcircuit scale is desirable. A pixel array unit 240 of a third embodimentis different from that of the first embodiment in that a monitor pixelcircuit 260 detects a bottom potential Vbtm instead of a light-shieldingpixel circuit 250.

FIG. 15 is an example of a circuit diagram of a control circuit 210 andthe monitor pixel circuit 260 according to the third embodiment of thepresent technology. The monitor pixel circuit 260 of the thirdembodiment is different from that of the first embodiment in that aresistor 265 is provided instead of the resistor 261. Furthermore, acathode of a photodiode 262 is connected to an inverting input terminal(−) of a comparator 211. Furthermore, the control circuit 210 is notprovided with a correction diode 212, and the light-shielding pixelcircuit 250 is not provided with a capacitor 253 and a diode 252.

A resistance value of the resistor 265 is smaller than that of aresistor 281 in the non-monitor pixel circuit 280, and is set to a valueat which an avalanche breakdown occurs even in a dark state where nolight enters the photodiode 262. Thereby, a value of a photocurrentI_(L) is fixed (in other words, latched) to a similar value to a valueat the incidence of light even in the dark state. Therefore, a potentialof a cathode is fixed to a bottom potential Vbtm, and the controlcircuit 210 can control an anode potential VSPAD according to thepotential.

As described above, according to the third embodiment of the presenttechnology, the monitor pixel circuit 260 detects the bottom potentialVbtm, and thus the capacitor 253 and the diode 252 can be reduced.Thereby, the circuit scale of the pixel array unit 240 can be reduced.

4. Fourth Embodiment

In the above-described first embodiment, the solid-state image sensor200 has detected the bottom potential Vbtm using the light-shieldingpixel circuit 250 provided with the capacitor 253 and the diode 252.However, there is a possibility of an increase in circuit scale due toaddition of the circuit such as the capacitor 253. From the viewpoint ofreducing a mounting area of the solid-state image sensor 200, a smallcircuit scale is desirable. A solid-state image sensor 200 of a fourthembodiment is different from that of the first embodiment in that acontrol circuit 210 estimates a bottom potential Vbtm from an outputvalue of a monitor pixel circuit 260.

FIG. 16 is an example of a circuit diagram of a monitor pixel circuit260 according to the fourth embodiment of the present technology. Themonitor pixel circuit 260 of the fourth embodiment is different fromthat of the first embodiment in including a comparator 266 instead ofthe inverter 263. Furthermore, a cathode of a photodiode 262 is notconnected to a light-shielding pixel circuit 250, and thelight-shielding pixel circuit 250 is not provided with a capacitor 253and a diode 252.

A non-inverting input terminal (+) of the comparator 266 is connected toa cathode of the photodiode 262, and an inverting input terminal (−) ofthe comparator 266 is connected to a power supply terminal having apredetermined potential (such as 0.1 volts). The comparator 266 comparesa potential of the cathode with a predetermined potential and supplies acomparison result to the control circuit 210 as a switching signal SW.The switching signal SW becomes at a high level in a case where acathode potential Vs is higher than the predetermined potential, andbecomes at a low level in a case where the cathode potential Vs is equalto or lower than the predetermined potential.

FIG. 17 is a block diagram illustrating a configuration example of thecontrol circuit 210 according to the fourth embodiment of the presenttechnology. The control circuit 210 includes a controller 213 and apower integrated circuit (IC) 214 instead of the comparator 211 and thecorrection diode 212.

The controller 213 controls a potential supplied by the power IC 214according to the switching signal SW. Details of control content will bedescribed below. The power IC 214 supplies an anode potential VSPADaccording to the control of the controller 213.

FIG. 18 is a graph illustrating an example of a relationship between acathode potential and an anode potential according to the fourthembodiment of the present technology. In FIG. 18 , the vertical axisrepresents the cathode potential Vs, and the horizontal axis representsthe anode potential VSPAD.

In a case where the switching signal SW is at a high level (that is, thecathode potential Vs is higher than the predetermined potential), thebottom potential Vbtm is estimated not to be less than a threshold valueVT. At this time, the controller 213 causes the power IC 214 to supply atarget value VL. On the other hand, in a case where the switching signalSW is at a low level (that is, the cathode potential Vs is equal to orlower than the predetermined potential), the bottom potential Vbtm isestimated to be less than the threshold value VT. At this time, thecontroller 213 causes the power IC 214 to supply a target value VH. Thistarget value VH is set to a value higher than the target value VL. Bythe control according to the switching signal SW, a lower anodepotential VSPAD is supplied as the bottom potential Vbtm is higher.

As described above, according to the fourth embodiment of the presenttechnology, the control circuit 210 estimates the bottom potential Vbtmfrom the comparison result between the cathode potential Vs and thepredetermined potential, and thus the capacitor 253 and the diode 252can be reduced. Thereby, the circuit scale of the pixel array unit 240can be reduced.

5. Fifth Embodiment

In the above-described first embodiment, the solid-state image sensor200 has detected the bottom potential Vbtm using the light-shieldingpixel circuit 250 provided with the capacitor 253 and the diode 252.However, there is a possibility of an increase in circuit scale due toaddition of the circuit such as the capacitor 253. From the viewpoint ofreducing a mounting area of the solid-state image sensor 200, a smallcircuit scale is desirable. A solid-state image sensor 200 of a fifthembodiment differs from that of the first embodiment in that a controlcircuit 210 estimates a bottom potential Vbtm from a count value of apulse signal OUT of a monitor pixel circuit 260.

FIG. 19 is an example of a circuit diagram of the monitor pixel circuit260 according to the fifth embodiment of the present technology. Themonitor pixel circuit 260 in the fifth embodiment is different from thatof the first embodiment in that a transistor 267 is provided instead ofthe resistor 261, and an inverter 263 supplies the pulse signal OUT tothe control circuit 210. Furthermore, a cathode of a photodiode 262 isnot connected to a light-shielding pixel circuit 250, and thelight-shielding pixel circuit 250 is not provided with a capacitor 253and a diode 252.

For example, as the transistor 267, a pMOS transistor is used.Furthermore, a low-level bias voltage Vb is applied to a gate of thetransistor 267. Note that an on-resistance of the transistor 267 is anexample of a resistor described in the claims.

FIG. 20 is a block diagram illustrating a configuration example of thecontrol circuit 210 according to the fifth embodiment of the presenttechnology. The control circuit 210 of the fifth embodiment is differentfrom that of the first embodiment in including a controller 213, a powerIC 214, a comparison unit 215, and a counter 216 instead of thecomparator 211 and the correction diode 212.

The counter 216 counts the number of times of when the pulse signal OUTbecomes at a high level within a period of a vertical synchronizationsignal VSYNC. The counter 216 supplies a count value to the comparisonunit 215.

The comparison unit 215 compares the count value with a predeterminedfixed value. The comparison unit 215 supplies a comparison result to thecontroller 213 as a switching signal SW. For example, the switchingsignal SW becomes at a high level in a case where the count value islarger than the fixed value, and becomes at a low level in a case wherethe count value is equal to or smaller than the fixed value.

The controller 213 controls a potential supplied by the power IC 214according to the switching signal SW. Details of control content will bedescribed below. The power IC 214 supplies an anode potential VSPADaccording to the control of the controller 213.

FIG. 21 is a graph illustrating an example of a relationship between thecount value and the anode potential according to the fifth embodiment ofthe present technology. In FIG. 21 , the vertical axis represents thecount value, and the horizontal axis represents the anode potentialVSPAD.

The switching signal SW being at a low level (that is, the count valuebeing the fixed value or less) means that the number of times of whenthe bottom potential Vbtm becomes less than the threshold value VT issmall. At this time, the controller 213 causes the power IC 214 tosupply a target value VL. On the other hand, the switching signal SWbeing at a high level (that is, the count value being larger than thefixed value) means that the number of times of when the bottom potentialVbtm becomes less than the threshold value VT is large. At this time,the controller 213 causes the power IC 214 to supply a target value VH.This target value VH is set to a value higher than the target value VL.

As described above, according to the fifth embodiment of the presenttechnology, the control circuit 210 controls the anode potential VSPADon the basis of the comparison result between the count value accordingto the bottom potential Vbtm and the fixed value, and thus the capacitor253 and the diode 252 can be reduced. Thereby, the circuit scale of thepixel array unit 240 can be reduced.

6. Sixth Embodiment

In the above-described first embodiment, the solid-state image sensor200 has detected the bottom potential Vbtm using the light-shieldingpixel circuit 250 provided with the capacitor 253 and the diode 252.However, there is a possibility of an increase in circuit scale due toaddition of the circuit such as the capacitor 253. From the viewpoint ofreducing a mounting area of the solid-state image sensor 200, a smallcircuit scale is desirable. A solid-state image sensor 200 of a sixthembodiment is different from that of the first embodiment in that acontrol circuit 210 estimates a bottom potential Vbtm from a pulse widthof a monitor pixel circuit 260.

FIG. 22 is a block diagram illustrating a configuration example of thecontrol circuit 210 according to the sixth embodiment of the presenttechnology. The control circuit 210 of the sixth embodiment is differentfrom that of the first embodiment in including a controller 213, a powerIC 214, and a pulse width detection unit 217 instead of the comparator211 and the correction diode 212. Furthermore, a cathode of a photodiode262 is not connected to a light-shielding pixel circuit 250, and thelight-shielding pixel circuit 250 is not provided with a capacitor 253and a diode 252.

The pulse width detection unit 217 detects a pulse width of a pulsesignal OUT from the monitor pixel circuit 260. The pulse width detectionunit 217 supplies the detected pulse width to the controller 213.

The controller 213 controls a potential supplied from the power IC 214on the basis of the pulse width. Details of control content will bedescribed below. The power IC 214 supplies an anode potential VSPADaccording to the control of the controller 213.

FIG. 23 is a timing chart illustrating an example of operations of thecontrol circuit 210 and the monitor pixel circuit 260 according to thesixth embodiment of the present technology.

The pulse width detection unit 217 supplies a high-level gate signal GATover a predetermined pulse period at the start of distance measurementor before the start of distance measurement. At this time, thecontroller 213 holds the pulse width detected by the pulse widthdetection unit 217 as a reference value.

Then, each time reflected light is received, the pulse width detectionunit 217 detects the pulse width, and the controller 213 compares thepulse width with the reference value. This pulse width tends to becomewider as the bottom potential Vbtm is lower. The controller 213 causesthe power IC 214 to supply a target value VL in a case where the pulsewidth is wider than the reference value on the basis of the tendency. Onthe other hand, in a case where the pulse width is equal to or smallerthan the reference value, the controller 213 causes the power IC 214 tosupply a target value VH. This target value VH is set to a value higherthan the target value VL.

As described above, according to the sixth embodiment of the presenttechnology, the control circuit 210 controls the anode potential VSPADon the basis of the comparison result between the pulse width accordingto the bottom potential Vbtm and the reference value, and thus thecapacitor 253 and the diode 252 can be reduced. Thereby, the circuitscale of the pixel array unit 240 can be reduced.

7. Seventh Embodiment

In the above-described first embodiment, the control circuit 210 hascontrolled the anode potential VSPAD using the comparator 211 that is ananalog circuit. However, since an analog circuit is generally larger incircuit scale than a digital circuit, a mounting area may increase. Acontrol circuit 210 of a seventh embodiment is different from that ofthe first embodiment in that an anode potential VSPAD is controlled by adigital circuit.

FIG. 24 is a block diagram illustrating a configuration example of thecontrol circuit 210 according to the seventh embodiment of the presenttechnology. The control circuit 210 is different from that of the firstembodiment in including a controller 213, a power IC 214, and an analogto digital converter (ADC) 218 instead of the comparator 211 and thecorrection diode 212.

The ADC 218 receives an excess bias dV that is a difference between apotential VE and a bottom potential Vbtm. The ADC 218 performs analog todigital (AD) conversion for the excess bias dV and supplies a digitalsignal to the controller 213. Since the potential VE is constant, theexcess bias dV takes a higher value as the bottom potential Vbtm islower.

The controller 213 controls a potential supplied from the power IC 214on the basis of the excess bias dV. The controller 213 causes the powerIC 214 to supply a lower anode potential VSPAD as the excess bias dV islower (that is, the bottom potential Vbtm is higher). The power IC 214supplies the anode potential VSPAD according to the control of thecontroller 213.

As described above, in the seventh embodiment of the present technology,the control circuit 210 controls the anode potential VSPAD by thecontroller 213 and the power IC 214. Therefore, the circuit scale can bereduced as compared with a case of using an analog circuit.

8. Eighth Embodiment

In the above-described seventh embodiment, the solid-state image sensor200 has only one monitor pixel circuit 260 disposed in the pixel arrayunit 240, but there is a possibility of a failure of the monitor pixelcircuit 260 due to, for example, deterioration over time, and the pixelbecomes a defective pixel. A pixel array unit 240 of an eighthembodiment is different from that of the seventh embodiment in arranginga plurality of monitor pixel circuits 260 and enabling any one of themonitor pixel circuits 260.

In the pixel array unit 240 of the eighth embodiment, the plurality ofmonitor pixel circuits 260 is arranged as in the second embodimentillustrated in FIG. 13 .

FIG. 25 is an example of a circuit diagram of the monitor pixel circuit260 according to the eighth embodiment of the present technology. Themonitor pixel circuit 260 of the eighth embodiment is different fromthat of the seventh embodiment in including a transistor 267 instead ofthe resistor 261. Furthermore, the monitor pixel circuit 260 of theeighth embodiment is different from that of the seventh embodiment inincluding switches 268 and 270, an inverter 269, a diode 271, and alatch circuit 272 instead of the transistor 264.

For example, as the transistor 267, a pMOS transistor is used.Furthermore, a low-level bias voltage Vb is applied to a gate of thetransistor 267. Note that an on-resistance of the transistor 267 is anexample of a resistor described in the claims.

The latch circuit 272 holds an enable signal EN from the control circuit210. The enable signal EN is a signal for enabling or disabling themonitor pixel circuit 260. For example, the enable signal EN is set to ahigh level in a case of enabling the monitor pixel circuit 260, and isset to a low level in a case of disabling the monitor pixel circuit 260.

The inverter 269 inverts the enable signal EN held in the latch circuit272 and outputs the inverted enable signal EN to the switch 268 as aninverted signal.

The switch 268 opens and closes a path between a cathode of a photodiode262 and a ground terminal according to the inverted signal from theinverter 269. For example, the switch 268 moves to a closed state in thecase where the inverted signal is at a high level, and moves to an openstate in the case where the inverted signal is at a low level.

The switch 270 opens and closes a path between the cathode of thephotodiode 262 and a cathode of the diode 271 according to the enablesignal EN held in the latch circuit 272. For example, the switch 270moves to a closed state in the case where the enable signal EN is at ahigh level, and moves to an open state in the case where the enablesignal EN is at a low level. An anode of the diode 271 is connected tothe light-shielding pixel circuit 250.

The controller 213 of the eighth embodiment selects and enables any oneof the plurality of monitor pixel circuits 260 by the enable signal EN,and disables the remaining monitor pixel circuits 260. The enabledmonitor pixel circuit 260 supplies a cathode potential Vs to thelight-shielding pixel circuit 250, the cathode potential Vs having apotential that drops due to incident light. Meanwhile, the disabledmonitor pixel circuit 260 has no avalanche breakdown in the photodiode262 by discharge from the switch 268 in the closed state, and does notoutput the cathode potential Vs by the switch 270 in the open state.

Furthermore, the controller 213 periodically switches the enabledmonitor pixel circuit 260. For example, the enabled monitor pixelcircuit 260 is switched every period of a vertical synchronizationsignal VSYNC. Since the avalanche breakdown does not occur in thephotodiode 262 of the disabled monitor pixel circuit 260, thedeterioration of the photodiode 262 can be suppressed by periodicallyenabling only any one of the monitor pixel circuits 260 as compared withthe case of always enabling all the monitor pixel circuits 260.

As described above, in the eighth embodiment of the present technology,the control circuit 210 enables any one of the plurality of monitorpixel circuits 260 and controls the anode potential VSPAD. Therefore,deterioration of the photodiode 262 can be suppressed as compared withthe case of enabling all the monitor pixel circuits 260.

9. Ninth Embodiment

In the above-described first embodiment, the light-shielding pixelcircuit 250 has detected the bottom potential Vbtm. However, asillustrated in FIG. 8 , there is a possibility of occurrence of an errorin the value of the bottom potential Vbtm. A monitor pixel circuit 260of a ninth embodiment is different from that of the first embodiment inadding a variable capacitor to reduce an error of a bottom potentialVbtm.

FIG. 26 is an example of a circuit diagram of a monitor pixel circuit260 according to the ninth embodiment of the present technology. Themonitor pixel circuit 260 of the ninth embodiment is different from thatof the first embodiment in including a transistor 267 instead of theresistor 261 and further including a variable capacitor 273.

For example, as the transistor 267, a pMOS transistor is used.Furthermore, a low-level bias voltage Vb is applied to a gate of thetransistor 267. Note that an on-resistance of the transistor 267 is anexample of a resistor described in the claims.

The variable capacitor 273 is a capacitor having a variable capacitancevalue. One end of the variable capacitor 273 is connected to a cathodeof a photodiode 262, and the other end of the variable capacitor 273 isconnected to a ground terminal.

Since the variable capacitor 273 is connected in parallel with acapacitor 253 in a light-shielding pixel circuit 250, a combinedcapacitance thereof is larger than that of a case of the capacitor 253alone. For this reason, the addition of the variable capacitor 273 canreduce the error of the bottom potential Vbtm. A capacitance value ofthe variable capacitor 273 is adjusted by a user or the like beforedistance measurement.

FIG. 27 is a timing chart illustrating an example of a bottom potentialaccording to the ninth embodiment of the present technology. a in FIG.27 illustrates a timing chart illustrating an example of the bottompotential detected in a comparative example without the variablecapacitor 273. b in FIG. 27 illustrates a timing chart illustrating anexample of the bottom potential detected in the ninth embodiment.

In the comparative example, the bottom potential Vbtm detected by thelight-shielding pixel circuit 250 does not coincide with an actualminimum value (that is, a true value) of a cathode potential Vs, and anerror occurs. Meanwhile, in the ninth embodiment, the bottom potentialVbtm substantially coincides with the true value, and the error isreduced.

As described above, in the ninth embodiment of the present technology,the variable capacitor 273 is connected in parallel with the capacitor253, and thus the circuit capacitance can be increased as compared witha case of using only the capacitor 253. Thereby, the error of the bottompotential Vbtm can be reduced.

10. Tenth Embodiment

In the above-described first embodiment, the light-shielding pixelcircuit 250 has detected the bottom potential Vbtm. However, asillustrated in FIG. 8 , there is a possibility of occurrence of an errorin the value of the bottom potential Vbtm. A monitor pixel circuit 260of a tenth embodiment is different from that of the first embodiment inreducing an error of a bottom potential Vbtm by applying a refresh pulsesignal.

FIG. 28 is an example of a circuit diagram of a monitor pixel circuit260 according to the tenth embodiment of the present technology. Thetenth monitor pixel circuit 260 is different from that of the firstembodiment in further including a transistor 274.

For example, as the transistor 274, a pMOS transistor is used. Thetransistor 274 short-circuits both ends of a resistor 261 according to arefresh pulse signal REF.

FIG. 29 is an example of a circuit diagram of a control circuit 210according to the tenth embodiment of the present technology. The controlcircuit 210 of the tenth embodiment is different from that of the firstembodiment in further including a refresh pulse supply unit 219.

The refresh pulse supply unit 219 supplies the refresh pulse signal REFto the monitor pixel circuit 260 in synchronization with a lightemission control signal CLKp.

FIG. 30 is a timing chart illustrating an example of fluctuations in thelight emission control signal CLKp, the refresh pulse signal REF, and abottom potential Vbtm according to the tenth embodiment of the presenttechnology.

At timing Tr immediately before rising timing Tp of the light emissioncontrol signal CLKp, the refresh pulse supply unit 219 supplies thelow-level refresh pulse signal REF over a certain pulse period. Exceptfor the pulse period, the refresh pulse signal REF is set to a highlevel. By the low-level refresh pulse signal REF, the bottom potentialVbtm rises to the potential VE, and the capacitor 253 is charged. Sincea discharge time of the capacitor 253 is shortened by the period fromthe timing Tr to Tp, the amount of fluctuation of the bottom potentialVbtm due to the discharge becomes small, and the error of the bottompotential Vbtm is reduced.

As described above, in the tenth embodiment of the present technology,the control circuit 210 supplies the refresh pulse signal REF to chargethe capacitor 253. Therefore, the discharge time of the capacitor 253can be shortened accordingly. Thereby, the error of the bottom potentialVbtm can be reduced.

11. Eleventh Embodiment

In the above-described first embodiment, the control circuit 210 hascontrolled the anode potential VSPAD according to the bottom potentialVbtm. However, the sensitivity of the photodiode 262 may fluctuate dueto a temperature change. Due to this fluctuation in sensitivity, thedetection efficiency of incident light may be reduced. A control circuit210 of an eleventh embodiment is different from that of the firstembodiment in controlling an anode potential VSPAD according to atemperature.

FIG. 31 is an example of a plan view of a pixel array unit 240 accordingto the eleventh embodiment of the present technology. The pixel arrayunit 240 of the eleventh embodiment is different from that of the firstembodiment in that monitor pixel circuits 260 are not arrayed.

FIG. 32 is a block diagram illustrating a configuration example of thecontrol circuit 210 according to the eleventh embodiment of the presenttechnology. The control circuit 210 of the eleventh embodiment includesa controller 213, a power IC 214, a comparison unit 215, a temperaturesensor 220, and a reverse bias set value storage unit 221.

The temperature sensor 220 measures the temperature in a distancemeasuring module 100. The temperature sensor 220 supplies a measurementvalue to the comparison unit 215. The comparison unit 215 compares themeasurement value with a predetermined fixed value and supplies acomparison result to the controller 213 as a switching signal SW. In acase where the temperature is higher than the fixed value, for example,the switching signal SW is set to a high level, and in a case where thetemperature is equal to or lower than the fixed value, the switchingsignal SW is set to a low level.

The reverse bias set value storage unit 221 stores a breakdown voltagemeasured in advance as a set value VBD.

The controller 213 controls a potential supplied by the power IC 214 onthe basis of the temperature and the set value VBD. Details of controlcontent will be described below. The power IC 214 supplies an anodepotential VSPAD according to the control of the controller 213.

FIG. 33 is a graph illustrating an example of a relationship betweentemperature and an anode potential according to the eleventh embodimentof the present technology. In FIG. 33 , the vertical axis represents themeasured temperature, and the horizontal axis represents the anodepotential VSPAD.

In a case where the switching signal SW is at a high level (that is, thetemperature is higher than the fixed value), the controller 213 sets atarget value VL by the following expression and supplies the targetvalue VL to the power IC 214.

VL=VE−(VBD+dVH)

In the above expression, dVH represents an excess bias of when thetemperature is relatively high.

Meanwhile, in a case where the switching signal SW is at a low level(that is, the temperature is equal to or lower than the fixed value),the controller 213 sets a target value VH by the following expressionand supplies the target value VH to the power IC 214.

VH=VE−(VBD+dVL)

In the above expression, dVL represents the excess bias of when thetemperature is relatively low, and is set to a value lower than dVH.

As described above, in the eleventh embodiment of the presenttechnology, the control circuit 210 controls the anode potential VSPADaccording to the temperature. Therefore, even if the sensitivity of thephotodiode 262 fluctuates due to a temperature change, the detectionefficiency of incident light can be maintained.

12. Application Example to Mobile Body

The technology according to the present disclosure (present technology)can be applied to various products. For example, the technologyaccording to the present disclosure may be realized as a device mountedon any type of moving bodies including an automobile, an electricautomobile, a hybrid electric automobile, a motorcycle, a bicycle, apersonal mobility, an airplane, a drone, a ship, a robot, and the like.

FIG. 34 is a block diagram illustrating a schematic configurationexample of a vehicle control system as an example of a moving bodycontrol system to which the technology according to the presentdisclosure is applicable.

A vehicle control system 12000 includes a plurality of electroniccontrol units connected through a communication network 12001. In theexample illustrated in FIG. 34 , the vehicle control system 12000includes a drive system control unit 12010, a body system control unit12020, a vehicle exterior information detection unit 12030, a vehicleinterior information detection unit 12040, and an integrated controlunit 12050. Furthermore, as functional configurations of the integratedcontrol unit 12050, a microcomputer 12051, a sound image output unit12052, and an in-vehicle network interface (I/F) 12053 are illustrated.

The drive system control unit 12010 controls operations of devicesregarding a drive system of a vehicle according to various programs. Forexample, the drive system control unit 12010 functions as a controldevice of a drive force generation device for generating drive force ofa vehicle, such as an internal combustion engine or a drive motor, adrive force transmission mechanism for transmitting drive force towheels, a steering mechanism that adjusts a steering angle of a vehicle,a braking device that generates braking force of a vehicle, and thelike.

The body system control unit 12020 controls operations of variousdevices equipped in a vehicle body according to various programs. Forexample, the body system control unit 12020 functions as a controldevice of a keyless entry system, a smart key system, an automaticwindow device, and various lamps such as head lamps, back lamps, brakelamps, turn signals, and fog lamps. In this case, radio wavestransmitted from a mobile device substituted for a key or signals ofvarious switches can be input to the body system control unit 12020. Thebody system control unit 12020 receives an input of the radio waves orthe signals, and controls a door lock device, the automatic windowdevice, the lamps, and the like of the vehicle.

The vehicle exterior information detection unit 12030 detectsinformation outside the vehicle that mounts the vehicle control system12000. For example, an imaging unit 12031 is connected to the vehicleexterior information detection unit 12030. The vehicle exteriorinformation detection unit 12030 causes the imaging unit 12031 tocapture an image outside the vehicle, and receives the imaged image. Thevehicle exterior information detection unit 12030 may perform objectdetection processing or distance detection processing of persons,vehicles, obstacles, signs, letters on a road surface, or the like onthe basis of the received image.

The imaging unit 12031 is an optical sensor that receives light andoutputs an electrical signal according to the amount of received light.The imaging unit 12031 can output the electrical signal as an image andcan output the electrical signal as information of distance measurement.Furthermore, the light received by the imaging unit 12031 may be visiblelight or may be non-visible light such as infrared light.

The vehicle interior information detection unit 12040 detectsinformation inside the vehicle. A driver state detection unit 12041 thatdetects a state of a driver is connected to the vehicle interiorinformation detection unit 12040, for example. The driver statedetection unit 12041 includes a camera that captures the driver, forexample, and the vehicle interior information detection unit 12040 maycalculate the degree of fatigue or the degree of concentration of thedriver, or may determine whether or not the driver falls asleep on thebasis of the detection information input from the driver state detectionunit 12041.

The microcomputer 12051 calculates a control target value of the drivepower generation device, the steering mechanism, or the braking deviceon the basis of the information outside and inside the vehicle acquiredin the vehicle exterior information detection unit 12030 or the vehicleinterior information detection unit 12040, and can output a controlcommand to the drive system control unit 12010. For example, themicrocomputer 12051 can perform cooperative control for the purpose ofrealizing the function of an advanced driver assistance system (ADAS)function including collision avoidance or shock mitigation of thevehicle, following travel based on an inter-vehicle distance, vehiclespeed maintaining travel, collision warning of the vehicle, lane outwarning of the vehicle, and the like.

Furthermore, the microcomputer 12051 controls the drive force generationdevice, the steering mechanism, the braking device, or the like on thebasis of the information of a vicinity of the vehicle acquired in thevehicle exterior information detection unit 12030 or the vehicleinterior information detection unit 12040 to perform cooperative controlfor the purpose of automatic drive of autonomous travel withoutdepending on an operation of the driver or the like.

Furthermore, the microcomputer 12051 can output a control command to thebody system control unit 12020 on the basis of the information outsidethe vehicle acquired in the vehicle exterior information detection unit12030. For example, the microcomputer 12051 can perform cooperativecontrol for the purpose of achievement of non-glare such as bycontrolling the head lamps according to the position of a leadingvehicle or an oncoming vehicle detected in the vehicle exteriorinformation detection unit 12030, and switching high beam light to lowbeam light.

The sound image output unit 12052 transmits an output signal of at leastone of a sound or an image to an output device that can visually andaurally notify a passenger of the vehicle or an outside of the vehicleof information. In the example in FIG. 34 , as the output device, anaudio speaker 12061, a display unit 12062, and an instrument panel 12063are exemplarily illustrated.

The display unit 12062 may include, for example, at least one of anon-board display or a head-up display.

FIG. 35 is a diagram illustrating an example of an installation positionof the imaging unit 12031.

In FIG. 35 , imaging units 12101, 12102, 12103, 12104, and 12105 areincluded as the imaging unit 12031.

The imaging units 12101, 12102, 12103, 12104, and 12105 are provided atpositions such as a front nose, side mirrors, a rear bumper, a backdoor, and an upper portion of a windshield in an interior of the vehicle12100, for example. The imaging unit 12101 provided at the front noseand the imaging unit 12105 provided at an upper portion of thewindshield in an interior of the vehicle mainly acquire front images ofthe vehicle 12100. The imaging units 12102 and 12103 provided at theside mirrors mainly acquire side images of the vehicle 12100. Theimaging unit 12104 provided at the rear bumper or the back door mainlyacquires a rear image of the vehicle 12100. The imaging unit 12105provided at the upper portion of the windshield in the interior of thevehicle is mainly used for detecting a preceding vehicle, a pedestrian,an obstacle, a traffic signal, a traffic sign, a lane, or the like.

Note that FIG. 35 illustrates an example of imaging ranges of theimaging units 12101 to 12104. An imaging range 12111 indicates theimaging range of the imaging unit 12101 provided at the front nose,imaging ranges 12112 and 12113 respectively indicate the imaging rangesof the imaging units 12102 and 12103 provided at the side mirrors, andan imaging range 12114 indicates the imaging range of the imaging unit12104 provided at the rear bumper or the back door. For example, abird's-eye view image of the vehicle 12100 as viewed from above can beobtained by superimposing image data captured by the imaging units 12101to 12104.

At least one of the imaging units 12101 to 12104 may have a function toacquire distance information. For example, at least one of the imagingunits 12101 to 12104 may be a stereo camera including a plurality ofimaging elements or may be an imaging element having pixels for phasedifference detection.

For example, the microcomputer 12051 obtains distances tothree-dimensional objects in the imaging ranges 12111 to 12114 andtemporal changes of the distances (relative speeds to the vehicle 12100)on the basis of the distance information obtained from the imaging units12101 to 12104, thereby to extract particularly a three-dimensionalobject closest to the vehicle 12100 on a traveling road and traveling ata predetermined speed (for example, 0 km/h or more) in substantially thesame direction as the vehicle 12100 as a leading vehicle. Moreover, themicrocomputer 12051 can set an inter-vehicle distance to be secured fromthe leading vehicle in advance and perform automatic braking control(including following stop control) and automatic acceleration control(including following start control), and the like. In this way, thecooperative control for the purpose of automatic drive of autonomoustravel without depending on an operation of the driver or the like canbe performed.

For example, the microcomputer 12051 classifies three-dimensional objectdata regarding three-dimensional objects into two-wheeled vehicles,ordinary cars, large vehicles, pedestrians, and other three-dimensionalobjects such as electric poles to be extracted, on the basis of thedistance information obtained from the imaging units 12101 to 12104, andcan use the data for automatic avoidance of obstacles. For example, themicrocomputer 12051 discriminates obstacles around the vehicle 12100into obstacles visually recognizable by the driver of the vehicle 12100and obstacles visually unrecognizable by the driver. Then, themicrocomputer 12051 determines a collision risk indicating a risk ofcollision with each of the obstacles, and can perform drive assist forcollision avoidance by outputting warning to the driver through theaudio speaker 12061 or the display unit 12062, and performing forceddeceleration or avoidance steering through the drive system control unit12010, in a case where the collision risk is a set value or more andthere is a collision possibility.

At least one of the imaging units 12101 to 12104 may be an infraredcamera that detects infrared light. For example, the microcomputer 12051determines whether or not a pedestrian exists in the imaged images ofthe imaging units 12101 to 12104, thereby to recognize the pedestrian.The recognition of a pedestrian is performed by a process of extractingcharacteristic points in the imaged images of the imaging units 12101 to12104, as the infrared camera, for example, and by a process ofperforming pattern matching processing for the series of characteristicpoints indicating a contour of an object and discriminating whether ornot the object is a pedestrian. When the microcomputer 12051 determinesthat a pedestrian exists in the imaged images of the imaging units 12101to 12104 and recognizes the pedestrian, the sound image output unit12052 causes the display unit 12062 to superimpose and display a squarecontour line for emphasis on the recognized pedestrian. Furthermore, thesound image output unit 12052 may cause the display unit 12062 todisplay an icon or the like representing the pedestrian at a desiredposition.

An example of a vehicle control system to which the technology accordingto the present disclosure is applicable has been described. Thetechnology according to the present disclosure is applicable to thevehicle exterior information detection unit 12030, of theabove-described configurations. Specifically, the distance measuringmodule 100 in FIG. 1 can be applied to the vehicle exterior informationdetection unit 12030. By applying the technology according to thepresent disclosure to the vehicle exterior information detection unit12030, an anode potential can be controlled to an appropriate value atwhich the erroneous count rate becomes small and the photon detectionefficiency becomes sufficiently high, and accurate distance informationcan be obtained.

Note that the above-described embodiments describe an example forembodying the present technology, and the matters in the embodiments andthe matters used to specify the invention in the claims havecorrespondence, respectively. Similarly, the matters used to specify theinvention in the claims and the matters in the embodiment of the presenttechnology given the same names have correspondence, respectively.However, the present technology is not limited to the embodiments, andcan be embodied by application of various modifications to theembodiments without departing from the gist of the present technology.

Further, the processing procedures described in the above embodimentsmay be regarded as a method having these series of procedures, and alsoregarded as a program for causing a computer to execute these series ofprocedures and as a recording medium for storing the program. As thisrecording medium, for example, a compact disc (CD), a mini disc (MD), adigital versatile disc (DVD), a memory card, a Blu-ray disc (Blu-ray(registered trademark) disc), or the like can be used.

Note that the effects described in the present specification are merelyexamples and are not limited, and other effects may be exhibited.

Note that the present technology can also have the followingconfigurations.

(1) A solid-state image sensor including:

a photodiode configured to photoelectrically convert incident light andoutput a photocurrent;

a resistor connected to a cathode of the photodiode; and

a control circuit configured to supply a lower potential to an anode ofthe photodiode as a potential of the cathode of when the photocurrentflows through the resistor is higher.

(2) The solid-state image sensor according to (1), further including:

a detection circuit configured to detect the potential of the cathode ofwhen the photocurrent flows through the resistor and supply the detectedpotential to the control circuit.

(3) The solid-state image sensor according to (2), in which

the resistor and the photodiode are disposed in each of a plurality ofpixel circuits,

the respective cathodes of the plurality of pixel circuits are commonlyconnected to the detection circuit, and

the detection circuit detects a minimum value of the respectivepotentials of the cathodes of when the photocurrent flows through theresistor.

(4) The solid-state image sensor according to (2) or (3), furtherincluding:

a variable capacitor connected to the cathode.

(5) The solid-state image sensor according to any one of (2) to (4),further including:

a transistor configured to short-circuit both ends of the resistoraccording to a refresh pulse signal, in which

the control circuit further supplies the refresh pulse signal to thetransistor immediately before incidence of the incident light.

(6) The solid-state image sensor according to (1), in which

a resistance value of the resistor is a value at which the potential ofthe cathode is fixed.

(7) The solid-state image sensor according to (1), further including:

a comparator configured to compare the potential of the cathode with apredetermined potential and output a comparison result, in which

the control circuit supplies, to the anode, a lower potential than apotential of a case where the potential of the cathode is less than thepredetermined potential, in a case where the potential of the cathode ishigher than the predetermined potential, on the basis of the comparisonresult.

(8) The solid-state image sensor according to (1), in which

the control circuit counts a number of times of when the potential ofthe cathode becomes lower than a predetermined threshold value in apredetermined period, and supplies, to the anode, a lower potential thana potential of a case where the number of times is larger than apredetermined number of times, in a case where the number of times isless than the predetermined number of times.

(9) The solid-state image sensor according to (1), further including:

an inverter configured to invert a signal of the potential of thecathode and output the signal as a pulse signal, in which

the control circuit supplies a lower potential to the anode of thephotodiode as a pulse width of the pulse signal is shorter.

(10) The solid-state image sensor according to (1), in which

one end of the resistor is connected to the cathode and the other end ofthe resistor is connected to a terminal of a predetermined potential,and

the control circuit measures a voltage between the potential of thecathode and the predetermined potential, and supplies a lower potentialto the anode of the photodiode as the voltage is higher.

(11) The solid-state image sensor according to (10), in which

the resistor and the photodiode are disposed in each of a plurality ofpixel circuits, and

the control circuit sets any one of the plurality of pixel circuits tobe enabled and measures the voltage between the potential of the cathodeof the set pixel circuit and the predetermined potential.

(12) A solid-state image sensor including:

a photodiode configured to photoelectrically convert incident light andoutput a photocurrent;

a resistor connected to a cathode of the photodiode; and

a control circuit configured to measure a temperature and supply a lowerpotential to an anode of the photodiode as the temperature is lower.

(13) An electronic device including:

a light emitting unit configured to supply irradiation light;

a photodiode configured to photoelectrically convert reflected lightwith respect to the irradiation light and output a photocurrent;

a resistor connected to a cathode of the photodiode; and

a control circuit configured to supply a lower potential to an anode ofthe photodiode as a potential of the cathode of when the photocurrentflows through the resistor is higher.

REFERENCE SIGNS LIST

-   100 Distance measuring module-   110 Light emitting unit-   120 Synchronization control unit-   200 Solid-state image sensor-   210 Control circuit-   211, 266 Comparator-   212 Correction diode-   213 Controller-   214 Power IC-   215 Comparison unit-   216 Counter-   217 Pulse width detection unit-   218 ADC-   219 Refresh pulse supply unit-   220 Temperature sensor-   221 Reverse bias set value storage unit-   230 Signal processing unit-   231 TDC-   232 Distance data generation unit-   240 Pixel array unit-   250 Light-shielding pixel circuit-   251, 261, 265, 281 Resistor-   252, 271 Diode-   253 Capacitor-   260 Monitor pixel circuit-   262, 282 Photodiode-   263, 269, 283 Inverter-   264, 267, 274, 284 Transistor-   268, 270 Switch-   272 Latch circuit-   273 Variable capacitor-   280 Non-monitor pixel circuit-   12030 Vehicle exterior information detection unit

1. (canceled)
 2. A light detecting device, comprising: first pixelcircuitry including a first avalanche photodiode and a first inverter,the first pixel circuitry configured to output a first output signal;second pixel circuitry including a second avalanche photodiode and asecond inverter ,the second pixel circuitry configured to output asecond output signal; and control circuitry configured to receive thesecond output signal, wherein an output of the control circuitry iscoupled to an anode of the first avalanche photodiode and an anode ofthe second avalanche photodiode.
 3. The light detecting device accordingto claim 2, wherein the control circuitry includes comparison circuitryconfigured to adjust the output based on the second output signal. 4.The light detecting device according to claim 2, wherein the secondavalanche photodiode is one of a plurality of second avalanchephotodiodes, the anode of the second avalanche photodiode is one of aplurality of anodes respectively corresponding to the plurality ofsecond avalanche diodes, and the output of the control circuitry iscoupled to the plurality of anodes.
 5. The light detecting deviceaccording to claim 4, wherein the plurality of second avalanchephotodiodes are disposed in a row.
 6. The light detecting deviceaccording to claim 2, wherein the first pixel circuitry and the secondpixel circuitry are arranged in an array, and a first part of the arrayis shielded from light.
 7. The light detecting device according to claim6, wherein a second part of the array is not shielded from light, andthe first avalanche photodiode and the second avalanche photodiode arelocated in the second part of the array.
 8. The light detecting deviceaccording to claim 2, wherein the first pixel circuitry further includesa transistor, one of a source or a drain of the transistor being coupledto a first potential.
 9. The light detecting device according to claim8, wherein the first inverter and the other of the source or the drainof the transistor are coupled to a cathode of the first avalanchephotodiode.
 10. The light detecting device according to claim 2, whereinthe second pixel circuitry includes a transistor, one of a source or adrain of the transistor being coupled to a first potential.
 11. Thelight detecting device according to claim 10, wherein the secondinverter and the other of the source or the drain of the transistor arecoupled to a cathode of the second avalanche photodiode.
 12. The lightdetecting device according to claim 2, wherein the first pixel circuitryincludes a first transistor, a source or a drain of the first transistorbeing coupled to a first potential, and the second pixel circuitryincludes a second transistor, a source or a drain of the secondtransistor being coupled to the first potential.
 13. A light detectingdevice, comprising: first pixel circuitry including a first avalanchephotodiode and a first inverter coupled to a first terminal of the firstavalanche photodiode, the first pixel circuitry configured to output afirst output signal; second pixel circuitry including a second avalanchephotodiode and a second inverter coupled to a first terminal of thesecond avalanche photodiode , the second pixel circuitry configured tooutput a second output signal; and control circuitry configured toreceive the second output signal, wherein an output of the controlcircuitry is coupled to a second terminal of the first avalanchephotodiode and a second terminal of the second avalanche photodiode. 14.The light detecting device according to claim 13, wherein the controlcircuitry includes comparison circuitry configured to adjust the outputbased on the second output signal.
 15. The light detecting deviceaccording to claim 13, wherein the second avalanche photodiode is one ofa plurality of second avalanche photodiodes, the second terminal of thesecond avalanche photodiode is one of a plurality of second terminalsrespectively corresponding to the plurality of second avalanche diodes,and the output of the control circuitry is coupled to the plurality ofsecond terminals.
 16. The light detecting device according to claim 15,wherein the plurality of second avalanche photodiodes are disposed in arow.
 17. The light detecting device according to claim 13, wherein thefirst pixel circuitry and the second pixel circuitry are arranged in anarray, and a first part of the array is shielded from light.
 18. Thelight detecting device according to claim 17, wherein a second part ofthe array is not shielded from light, and the first avalanche photodiodeand the second avalanche photodiode are located in the second part ofthe array.
 19. The light detecting device according to claim 13, whereinthe first pixel circuitry further includes a transistor, one of a sourceor a drain of the transistor being coupled to a first potential.
 20. Thelight detecting device according to claim 19, wherein the other of thesource or the drain of the transistor is coupled to the first terminalof the first avalanche photodiode.
 21. The light detecting deviceaccording to claim 13, wherein the second pixel circuitry includes atransistor, one of a source or a drain of the transistor being coupledto a first potential.
 22. The light detecting device according to claim21, wherein the other of the source or the drain of the transistor iscoupled to the first terminal of the second avalanche photodiode. 23.The light detecting device according to claim 13, wherein the firstpixel circuitry includes a first transistor, a source or a drain of thefirst transistor being coupled to a first potential, and the secondpixel circuitry includes a second transistor, a source or a drain of thesecond transistor being coupled to the first potential.
 24. A distancemeasuring apparatus comprising: a light emitting device; and the lightdetecting device according to claim
 2. 25. A distance measuringapparatus comprising: a light emitting device; and the light detectingdevice according to claim 13.